CM3.1 | CM3.1 | Environmental Pollution Hazards — Summary & Reflection

KEY TAKEAWAYS

Environmental pollution is a major modifiable cause of disease and death in India. Key points from this module:

• Air pollutants are classified as primary (directly emitted) or secondary (atmospherically formed); particulate matter is further classified by size—PM2.5 penetrates the alveoli and causes systemic cardiovascular harm.
• Carbon monoxide binds haemoglobin with 240× the affinity of oxygen, causing tissue hypoxia; pulse oximetry is unreliable for diagnosis.
• Lead is a cumulative neurotoxin with no safe blood level in children; blood lead ≥5 µg/dL triggers action.
• Water pollutants: arsenic >10 µg/L (WHO limit) causes keratoses and cancer; fluoride >1.5 mg/L causes dental fluorosis; nitrate >45 mg/L can cause methaemoglobinaemia in infants.
• Noise >85 dB(A) for 8 hours/day destroys cochlear hair cells irreversibly; community noise above WHO night-time limits (55 dB) increases cardiovascular risk.
• Ionising radiation causes deterministic (threshold) and stochastic (no-threshold) effects; radiation workers are limited to 20 mSv/year (India).
• India's NAAQS is more permissive than WHO 2021 guidelines—'legally compliant' air may still carry health risk.
• The National Clean Air Programme (NCAP) targets PM reduction in 122 cities by 2024.
• Clinicians must take an occupational/environmental history, counsel patients on AQI-based precautions, and report pollution disease clusters to IDSP.

REFLECT

Think about the patients you are likely to see in your future practice at a primary health centre or district hospital in India. How would you systematically identify which of your patients might be experiencing pollution-related illness? What questions would you add to a standard history-taking format? Consider the interplay between poverty, fuel choice, housing quality, and pollution exposure—how might addressing one social determinant simultaneously reduce multiple pollution hazards? If you were advising a municipal health committee on prioritising pollution control investments, which hazard category would you argue for first, and what evidence would you cite?